Tunable surface roughness and wettability of a soft magnetoactive elastomer

Abstract

Surface topographical modifications of a soft magnetoactive elastomer (MAE) in response to variable applied magnetic field are investigated. The analysis is performed insitu and is based on optical microscopy, spread optical reflection and optical profilometry measurements. Optical profilometry analysis shows that the sensitivity of magnetic fieldinduced surface roughness with respect to external magnetic field is in the range of 1 µm/T. A significant hysteresis of surface modifications takes place for increasing and decreasing fields. Investigations of shape of sessile water droplets deposited on the MAE surface reveal that field-induced topographical modifications affect the contact angle of water at the surface. This effect is reversible and the sensitivity to magnetic field is in the range of 20/T.

Surface relief of magnetoactive elastomeric films in a homogeneous magnetic field: molecular dynamics simulations

“…In other words, the layer thickness was approximately 20–40 particles diameters. Tunable surface roughness and wettability of soft MAEs have also been reported in ref. 33, however, despite the increased surface roughness, the apparent contact angle has shown to decrease with increasing field.…”

“…This fact has been attributed to the field-induced protrusion of hydrophilic iron particles from the surface layer. Anyway, the first reported results31–33 indicate that with MAEs it is possible not only to produce hydrophobic coatings by applying an external magnetic field in the course of curing, but also to dynamically tune the MAE wettability and control their magneto-hydrophobicity with magnetic fields. Stimuli-responsive surfaces like these attract much attention nowadays34–36 due to their potential for the creation of new materials with advanced properties like self-cleaning, anti-sticking, anti-fouling, anti-icing, anti-fogging, drag reduction, etc.…”

Magnetoresponsive Surfaces for Manipulation of Nonmagnetic Liquids: Design and Applications

“…Mater. [51,81,82] c) Optical micrographs showing the bending of a Ni micronail (leg length = 60 µm) in an external magnetic field.…”

“…These MRSs can change their surface roughness or local topology (e.g., a dent or a ridge) upon magnetic stimuli. [51,81,82]…”

“…[65][66][67] Several groups have developed MRSs with switchable roughness for liquid motion control. [51,54,[81][82][83][84] Magnetorheological (MR) Elastomers: An MR elastomer refers to the composite containing an elastomer matrix and magnetic particles. [85,86] As reported by Lee et al, when an MR elastomer film was subjected to a magnetic field, its surface roughness changed accordingly.…”